METHOD OF WELL REPAIR AT ISOLATION OF BEHIND--CASING FLOWS Russian patent published in 2014 - IPC E21B29/10 

FIELD: oil and gas industry.

SUBSTANCE: method includes identification of all data on the casing defective area and elimination of this area. When sump is equal to at least 5 m the following tool is assembled: a cutter equipped with retractable teeth, a jet nozzle, a drill-collar string, a drill string. The tool is run in into the well so that the teeth are located opposite the upper interval of the defective area, the pump unit and a power swivel are switched on. The process fluid is pumped under pressure of 9.0 MPa. The tool is rotated and cut into the upper interval of the defective area by the power swivel. Maintaining operational parameters of the pump unit and the power swivel the load for the cutter is selected by an axial movement of the tool downwards, the string is cut within the whole interval of the defective area. When the lower interval is reached the jet nozzle is lowered up to the upper interval of the defective area, a ball is dropped into the pipe string and excessive pressure is created in the tool. By the axial rotation of the tool and simultaneous rotation by the directed fluid stream in the whole perimeter of the cut section the rocks are washed out till they stop appearing at the well head. Back-flow of the well is done, cementing string is run in and the well is isolated.

EFFECT: improving efficiency of the well repair, reducing time of the well repair.

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